... the difference between the maximum and minimum thickness values of a slice or wafer. Wafer clamped.
Standard Definitions
Wafer flatness is determined by means of an interferometry measuring equipment using a focal plane on front surface as a reference plane (edge exclusion is 3 mm).
TTV (Total Thickness Variation)
TIR (Total Indicated Reading)
... the distance between the maximum and minimum distances of the median surface from a reference plane. Wafer clamped.
Bow
... a measure of concave or convex deformation of the median surface of a slice or wafer, independent of any thickness variation which may be present. Wafer unclamped.
Warp
... the difference between the maximum and minimum distances of the median surface of the slice or wafer from a reference plane. Wafer unclamped.
General Definitions
Lot - for the purpose of definitions,
a) all the wafers of nominally identical size and characteristics contained in a single shipment, or
b) subdivisions of large shipments consisting of wafers as above which have been identified by the supplier as constituting a lot, or
c) often refers to all wafers cut from a single boule.
Dopant - a chemical element, usually from the second, fourth, or sixth columns of the periodic table for the case of III-V compounds, incorporated in trace amounts in a semiconductor crystal to establish its conductivity type and resistivity.
Orthogonal Misorientation - in {100} wafers cut with intentionally "off-orientation”, the angle between the projection of the vector normal to the slice surface onto the {100} plane and the projection on that plane of the nearest direction. It refers to the error in the direction, not the magnitude of the off cut angle. SEMI-Standard value is ±5 degrees.
| Mandatory criteria | Optional criteria |
|---|---|
| Nominal diameter | Crystal growth method |
| Thickness (see applicable standards for various diameters) | Etch pit density |
| Total Thickness Variation (TTV) | Dopant type |
| Surface Orientation | Electrical resistivity |
| Lot acceptance procedures | Electron mobility |
| Certification | Carrier concentration |
| Packaging and Labeling | Surface condition |